11. SOA specifications are useful to the design engineer working on power circuits such as amplifiers and foldback circuits. 12. Gryphon 100-watt-per-channel class-A amplifiers dissipate over 400 watts per channel even with no signal applied to their inputs. 13. The LM358 is designed for general use as amplifiers , high-pass filters and low, band pass filters and analog adders. 14. A push pull amplifier draws little power with zero signal, compared to a class-A amplifier that draws constant power. 15. Some audiophile equipment, such as amplifiers , continues to be point-to-point wired using terminal pins, often in very small quantities. 16. Class-A amplifiers can be designed to have good linearity in both " single ended " and " push-pull " topologies. 17. FETs can also be used as amplifiers for large amounts of current using a small voltage as a control signal. 18. As amplifiers of the time did not produce much power, the speakers had to be extremely efficient to produce adequate loudness.19. This is because a push pull amplifier has a symmetric ( class A amplifiers , which are otherwise required for single-ended linear amplification. 20. Loudness compensation is difficult to implement, since the audio level at a listener's ears depends on speaker sensitivity as well as amplifier gain.
